1. Field of the Invention
In one embodiment, the present invention is a process for decorating an object with a sublimation ink using, as the ink support or transfer sheet, a heat shrink film imprinted with the desired sublimation ink decoration. In another embodiment, the present invention is a process for decorating an object with a sublimation ink using a conventional sublimation ink imprinted transfer sheet and then enclosing the object and transfer sheet in heat shrink film. According to either process, heating the heat shrink film provides both the pressure and the heat to transfer the decoration into the surface of the object or into a pre-applied coating on the object surface.
2. Description of Related Art
The technology for transfer printing with sublimation ink developed in the late 1950's. French Patent No. 1,223,330, issued in June 1960 and assigned to Filatures Prouvost of France, describes technology that became the basis for sublimation ink transfer printing of fabrics. In 1968, Sublistatic of Switzerland developed the first commercial transfer printing application using sublimation ink. The sublimation ink was first printed onto a paper carrier transfer sheet to be sublimated onto a polyester or polyester-containing textile by application of heat and pressure. Roger Lepoutry, a founding member of Sublistatic, is now a consultant for Kolorfusion International Inc., Englewood, Colo., the assignee of the present application.
The known process, as applied to printing fabrics, involves vapor phase printing using dispersed dyes printed on paper and applied to the textile materials under pressure at temperatures between about 280.degree. to about 400.degree. F. for approximately thirty seconds. Suitable dispersed dyes for this process come from three classes: azo dyes, nitroarylamine dyes and anthraquinone dyes. Dispersed dyes when heated sublime, changing from a solid state to a gaseous state without passing through a melted or liquid state. A common example of a form of sublimation is the vaporization of dry ice (solid carbon dioxide), which evaporates to a gas without melting.
Processing three-dimensional objects with a sublimation ink pattern that has been printed on paper is often unsatisfactory. Because the paper transfer sheet cannot properly deform along its principal axes to the shape of the three-dimensional object, irregularities appear in conforming the sheet to the object. The paper sheet creases or crumples when positioned in a vacuum around the object to be decorated. At the moment of sublimation, these creases transfer into the surface of the object, thus adversely affecting the quality of the image produced. The paper sublimation ink transfer sheet prevents satisfactory decoration of spherical, curved, ovoid or other irregularly shaped objects.
Other references to printing or decorating with sublimation inks have used various other transfer sheet materials. For example, Recher, et al., U.S. Pat. No. 4,997,506, issued Mar. 5, 1991, explains at col. 2, lines 62-63 that ". . . the support of the coloring agents is a paper support." British Patent No. 52710/70 relates at page, column 2, that ". . . the carrier material for the sublimable water-insoluble dyestuff will normally consist of a cellulosic sheet material, in particular paper, but may alternatively consist of a metal foil or a metal foil supported upon a cellulosic material." Masaki, U. S. Pat. No. 4,314,813, issued Feb. 9, 1982, states at col. 5, lines 25-30 that ". . . the material for the base sheet 1 is not particularly limited as far as it satisfies the aforementioned conditions, and wood free paper and laminated paper composed of a paper layer and an aluminum foil or a cellophane layer may be preferably used." Note that cellophane is a treated regenerated cellulose and is not heat shrinkable. Claveau, U. S. Pat. No. 5,308,426, issued May 3, 1994, discloses at col. 2, lines 7-10 that "The process of decoration according to the invention is carried out using an ink support made of an extensible air-permeable material such as for example a woven fabric, knitted fabric or sheet of non-woven material." Heat shrink films are air impermeable. There has been no teaching or suggestion that a heat shrink film material may be used as a sublimation ink support or transfer sheet.
In the Claveau process, a silicone membrane totally encapsulates the object to be decorated by sublimation ink printing. Vacuum draws the membrane into intimate contact with the object and heat is provided, for example, in a convection oven. The process, while providing decorated objects of exceptional brilliance, requires excessive time for proper vacuum application and for the object to reach a temperature at which sublimation inks transfer into the object surface. Also, the vacuum enclosure adds to the time, energy and expense of the process.
So, there is a need for a process of sublimation ink printing of objects that provides exceptional brilliance, clarity and intensity of color and pattern, while eliminating the need for separately applying pressure on the transfer sheet to the object. There is also a need for a transfer sheet that will conform to the object to achieve clear, distortion-free pattern decoration. And, in the process of sublimation ink printing of objects using conventional sublimation ink transfer sheets, such as paper, metal foil, cellophane and other traditional transfer sheet materials, there is a need to simplify the application of the heat and pressure needed for transfer printing.